Power-generating device and power-generating method using organic rankine cycle

ABSTRACT

A power-generating device using an organic Rankine cycle uses heat recovered from an exhaust gas treated in an exhaust gas treatment device, the power-generating device including a heat exchanger, an evaporator, a steam turbine, a power generator, a condenser, and a medium pump.

BACKGROUND OF THE INVENTION

The present invention relates to a heat recovery device and a heat recovery method. More particularly, the present invention relates to a heat recovery device and a heat recovery method capable of generating power with heat recovered from a low-temperature exhaust gas discarded from a power generation plant.

Various studies have been conducted regarding the effective use of heat generated in the process of power generation in a thermal power generation plant, and the like. For example, a high-temperature exhaust gas discharged from a coal fired boiler enters a gas-gas heater heat recovery device through a denitrification device and an air preheater, and heat thereof is recovered. After that, the exhaust gas passes through an induced draft fan, a desulfurization device, a gas-gas heater re-heater, and a desulfurization draft fan, and is finally discharged from a chimney pipe.

The temperature of the exhaust gas whose heat has been recovered by the gas-gas heater heat recovery device is about 150° C., and hence, the exhaust gas has a low temperature as a heat source for recovering heat further. Therefore, in the case in which a flue-gas desulfurization device is used, the heat of the low-temperature exhaust gas has been used only for raising the gas temperature of exhaust gas in the vicinity of a chimney outlet so as to prevent white mist of exhaust gas from being discharged from a chimney pipe.

Further, in the case in which the flue-gas desulfurization device is used, the heat of the exhaust gas has been used for water evaporation in an absorption tower. Therefore, the heat of the exhaust gas is discarded out of the system, and the amount of makeup water to be used in the flue-gas desulfurization device is increased.

As described above, although the low-temperature exhaust gas is used for preventing white mist or water evaporation, it is not used as a heat source. Considering energy efficiency, it is desired to reduce waste heat generated by power generation and to recover energy also from the low-temperature exhaust gas.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a power-generating device and a power-generating method for generating power with a low-temperature exhaust gas as a heat source.

In order to solve the above-mentioned problems, according to a first exemplary embodiment of the power-generating device of the present invention, there is provided a power-generating device, including an organic Rankine cycle system using heat recovered from an exhaust gas, in which the organic Rankine cycle system includes: an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD); a first heat exchanger provided between the air preheater and the electrostatic precipitator; a second heat exchanger provided between the electrostatic precipitator and the flue-gas desulfurization device, a first evaporator for evaporating an organic solvent through use of heat recovered by the first heat exchanger to generate steam; a second evaporator for evaporating an organic solvent through use of heat recovered by the second heat exchanger to generate steam; a steam turbine to be driven with steam generated by the first evaporator and the second evaporator; a power generator for generating power by a drive of the steam turbine; a condenser for condensing steam that has driven the steam turbine to obtain an organic solvent; and a medium pump for sending the condensed organic solvent from the condenser to the first evaporator and the second evaporator.

According to a second exemplary embodiment of the power-generating device of the present invention, there is provided a power-generating device, including an organic Rankine cycle system using heat recovered from an exhaust gas, in which the organic Rankine cycle system includes: an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD); a first evaporator provided between the air preheater and the electrostatic precipitator, for evaporating an organic solvent to generate steam; a second evaporator provided between the electrostatic precipitator and the flue-gas desulfurization equipment, for evaporating an organic solvent to generate steam; a steam turbine to be driven with steam generated by the first evaporator and the second evaporator; a power generator for generating power by a drive of the steam turbine; a condenser for condensing steam that has driven the steam turbine to obtain an organic solvent; and a medium pump for sending the condensed organic solvent from the condenser to the first evaporator and the second evaporator.

According to a third exemplary embodiment of the power-generating device of the present invention, there is provided a power-generating device, including an organic Rankine cycle system using heat recovered from an exhaust gas, in which the organic Rankine cycle system includes: an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD); a first heat exchanger provided between the air preheater and the electrostatic precipitator; a first evaporator for evaporating an organic solvent through use of heat recovered by the first heat exchanger to generate steam; a first steam turbine to be driven with steam generated by the first evaporator; a first power generator for generating power by a drive of the first steam turbine; a first condenser for condensing steam that has driven the first steam turbine to obtain an organic solvent; a first medium pump for sending the condensed organic solvent from the first condenser to the first evaporator; a second heat exchanger provided between the electrostatic precipitator and the flue-gas desulfurization device; a second evaporator for evaporating an organic solvent through use of heat recovered by the second heat exchanger to generate steam; a second steam turbine to be driven with steam generated by the second evaporator; a second power generator for generating power by a drive of the second steam turbine; a second condenser for condensing steam that has driven the second steam turbine to obtain an organic solvent; and a second medium pump for sending the condensed organic solvent from the second condenser to the second evaporator.

According to a fourth exemplary embodiment of the power-generating device of the present invention, there is provided a power-generating device, including an organic Rankine cycle system using heat recovered from exhaust gas, in which the organic Rankine cycle system includes: an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD); a first evaporator provided between the air preheater and the electrostatic precipitator, for evaporating an organic solvent to generate steam; a first steam turbine to be driven with steam generated by the first evaporator; a first power generator for generating power by a drive of the first steam turbine; a first condenser for condensing steam that has driven the first steam turbine to obtain an organic solvent; a first medium pump for sending the condensed organic solvent from the first condenser to the first evaporator; a second evaporator provided between the electrostatic precipitator and the flue-gas desulfurization device, for evaporating an organic solvent to generate steam; a second steam turbine to be driven with steam generated by the second evaporator; a second power generator for generating power by a drive of the second steam turbine; a second condenser for condensing steam that has driven the second steam turbine to obtain an organic solvent; and a second medium pump for sending the condensed organic solvent from the second condenser to the second evaporator.

Further, according to a first exemplary embodiment of the power-generating method of the present invention, there is provided a power-generating method, including a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated by an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD), in which the step of executing an organic Rankine cycle includes: a first heat recovery step of recovering heat from an exhaust gas that passes between the air preheater and the electrostatic precipitator; a second heat recovery step of recovering heat from an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device; a first steam generation step of evaporating an organic solvent through use of heat recovered in the first heat recovery step to generate steam; a second steam generation step of evaporating an organic solvent through use of heat recovered in the second heat recovery step to generate steam; a steam turbine drive step of driving a steam turbine with steam generated in the first steam generation step and the second steam generation step; a power generation step of generating power in the steam turbine drive step; a condensing step of condensing steam that has driven the steam turbine to obtain an organic solvent; and a transport step of sending the organic solvent obtained by the condensation to the first steam generation step and the second steam generation step.

Further, according to a second exemplary embodiment of the power-generating method of the present invention, there is provided a power-generating method, including a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated by an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD), in which the step of executing an organic Rankine cycle includes: a first steam generation step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the air preheater and the electrostatic precipitator to generate steam; a second steam generation step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device to generate steam; a steam turbine drive step of driving a steam turbine with steam generated in the first steam generation step and the second steam generation step; a power generation step of generating power in the steam turbine drive step; a condensing step of condensing steam that has driven the steam turbine to obtain an organic solvent; and a transport step of sending the organic solvent obtained by the condensation to the first steam generation step and the second steam generation step.

Further, according to a third exemplary embodiment of the power-generating method of the present invention, there is provided a power-generating method, including a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated by an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD), in which the step of executing an organic Rankine cycle includes: a first heat recovery step of recovering heat from an exhaust gas that passes between the air preheater and the electrostatic precipitator; a first steam generation step of evaporating an organic solvent through use of heat recovered in the first heat recovery step to generate steam; a first steam turbine drive step of driving a first steam turbine with steam generated in the first steam generation step; a first power generation step of generating power in the first steam turbine drive step; a first condensing step of condensing steam that has driven the first steam turbine to obtain an organic solvent; a first transport step of sending the organic solvent obtained by the condensation to the first steam generation step; a second heat recovery step of recovering heat from an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device; a second steam generation step of evaporating an organic solvent through use of heat recovered in the second heat recovery step to generate steam; a second steam turbine drive step of driving a second steam turbine with steam generated in the second steam generation step; a second power generation step of generating power in the second steam turbine drive step; a second condensing step of condensing steam that has driven the second steam turbine to obtain an organic solvent; and a second transport step of sending the organic solvent obtained by the condensation to the second steam generation step.

Further, according to a fourth exemplary embodiment of the power-generating method of the present invention, there is provided a power-generating method, including a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated by an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD), in which the step of executing an organic Rankine cycle includes: a first steam generation step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the air preheater and the electrostatic precipitator to generate steam; a first steam turbine drive step of driving a first steam turbine with steam generated in the first steam generation step; a first power generation step of generating power in the first steam turbine drive step; a first condensing step of condensing steam that has driven the first steam turbine to obtain an organic solvent; a first transport step of sending the organic solvent obtained by the condensation to the first steam generation step; a second steam generation step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device to generate steam; a second steam turbine drive step of driving a second steam turbine with steam generated in the second steam generation step; a second power generation step of generating power in the second steam turbine drive step; a second condensing step of condensing steam that has driven the second steam turbine to obtain an organic solvent; and a second transport step of sending the organic solvent obtained by the condensation to the second steam generation step.

According to the power-generating device and the power-generating method of the present invention, heat of a low-temperature exhaust gas that used to be waste heat can be recovered to generate power, and the amount of power generation of the entire power generation plant can be increased. The power obtained by the power generation can be used as a part of power required in an environmental device such as a flue-gas desulfurization device. Further, the consumption amount of makeup water in the flue-gas desulfurization device can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a power-generating device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a power-generating device according to another embodiment of the present invention in a form different from that of FIG. 1.

FIG. 3 is a schematic diagram of a power-generating device according to still another embodiment of the present invention in a form different from those of FIGS. 1 and 2.

FIG. 4 is a schematic diagram of a power-generating device according to another embodiment of the present invention in a form different from those of FIGS. 1, 2, and 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a general form of a power-generating device and a power-generating method according to the present invention is described in detail. Note that, the present invention is not limited by embodiments herein. Further, constituent elements in the following embodiments include elements which can be replaced by those skilled in the art and which are easy, or elements which are substantially the same.

First, the power-generating device of the present invention includes an organic Rankine cycle system using heat recovered from an exhaust gas.

As one embodiment mode of the power-generating device of the present invention, the organic Rankine cycle system includes an exhaust gas treatment device, a first heat exchanger, a second heat exchanger, a first evaporator, a second evaporator, a steam turbine, a power generator, a condenser, and a medium pump.

The exhaust gas treatment device includes an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD). The power-generating device of the present invention uses an exhaust gas to be treated by the exhaust gas treatment device as a heat source to generate power through use of heat recovered from the exhaust gas.

The first heat exchanger is provided between the air preheater and the electrostatic precipitator and recovers heat from an exhaust gas that moves from the air preheater to the electrostatic precipitator. The first heat exchanger can recover heat until an exhaust gas at about 150° C. is lowered to about 90° C.

The second heat exchanger is provided between the electrostatic precipitator and the flue-gas desulfurization device and recovers heat from an exhaust gas that moves from the electrostatic precipitator to the flue-gas desulfurization device. The second heat exchanger can recover heat until an exhaust gas at about 90° C. is lowered to about 60° C.

The first evaporator evaporates an organic solvent through use of heat recovered by the first heat exchanger to generate steam. As the organic solvent, a solvent having a low boiling point, which is to be evaporated with heat recovered from a low-temperature exhaust gas, is used. Examples of the organic solvent include ammonia, hydrochlorofluorocarbon, and hydrocarbon.

The second evaporator evaporates an organic solvent through use of heat recovered by the second heat exchanger to generate steam. As the organic solvent, a solvent having a low boiling point, which is to be evaporated with heat recovered from a low-temperature exhaust gas, is used. Examples of the organic solvent include ammonia, hydrochlorofluorocarbon, and hydrocarbon.

The steam turbine is driven with steam generated by the first evaporator and the second evaporator. The steam turbine converts energy of the steam into a rotation movement via blades.

The power generator generates power by the drive of the steam turbine. The power generator obtains electric energy from mechanical energy that is a rotation movement.

The condenser condenses steam that has driven the steam turbine to obtain an organic solvent.

The medium pump is a pump that sends the condensed organic solvent from the condenser to the first evaporator and the second evaporator.

The above-mentioned power-generating device according to the present invention can include a cooling tower. The cooling tower is a facility for circulating cooling water in the condenser, and can efficiently condense steam in the condenser by cooling with water.

As another embodiment mode different from the above-mentioned embodiment mode of the power-generating device of the present invention, the organic Rankine cycle system includes an exhaust gas treatment device, a first evaporator, a second evaporator, a steam turbine, a power generator, a condenser, and a medium pump.

The first evaporator is provided between the air preheater and the electrostatic precipitator, and evaporates an organic solvent through use of heat of an exhaust gas that moves from the air preheater to the electrostatic precipitator to generate steam. As the organic solvent, a solvent having a low boiling point, which is to be evaporated with heat recovered from a low-temperature exhaust gas, is used. Examples of the organic solvent include ammonia, hydrochlorofluorocarbon, and hydrocarbon.

The second evaporator is provided between the electrostatic precipitator and the flue-gas desulfurization device, and evaporates an organic solvent through use of heat of an exhaust gas that moves from the electrostatic precipitator to the flue-gas desulfurization device to generate steam. As the organic solvent, a solvent having a low boiling point, which is to be evaporated with heat recovered from a low-temperature exhaust gas, is used. Examples of the organic solvent include ammonia, hydrochlorofluorocarbon, and hydrocarbon.

The exhaust gas treatment device, the steam turbine, the power generator, the condenser, and the medium pump are as described above.

The above-mentioned power-generating device according to the present invention can include a cooling tower for circulating cooling water in the condenser.

As still another embodiment mode different from the above-mentioned embodiment modes of the power-generating device of the present invention, the organic Rankine cycle system includes an exhaust gas treatment device, a first heat exchanger, a first evaporator, a first steam turbine, a first power generator, a first condenser, a first medium pump, a second heat exchanger, a second evaporator, a second steam turbine, a second power generator, a second condenser, and a second medium pump. The exhaust gas treatment device is as described above.

The exhaust gas treatment device, the first heat power exchanger, the first evaporator, the first steam turbine, the first power generator, the first condenser, the first medium pump constitute one organic Rankine cycle. Further, the exhaust gas treatment device, the second heat exchanger, the second evaporator, the second steam turbine, the second power generator, the second condenser, and the second medium pump constitute another organic Rankine cycle.

The first heat exchanger is provided between the air preheater and the electrostatic precipitator and recovers heat from an exhaust gas that moves from the air preheater to the electrostatic precipitator. The first heat exchanger can recover heat until an exhaust gas at about 150° C. is lowered to about 90° C.

The first evaporator evaporates an organic solvent through use of heat recovered by the first heat exchanger to generate steam. As the organic solvent, a solvent having a low boiling point, which is to be evaporated with heat recovered from a low-temperature exhaust gas, is used. Examples of the organic solvent include ammonia, hydrochlorofluorocarbon, and hydrocarbon.

The first steam turbine is driven with steam generated by the first evaporator. The steam turbine converts energy of the steam into a rotation movement via blades.

The first power generator generates power by the drive of the first steam turbine. The first power generator obtains electric energy from mechanical energy that is a rotation movement.

The first condenser condenses steam that has driven the first steam turbine to obtain an organic solvent.

The first medium pump is a pump that sends the condensed organic solvent from the first condenser to the first evaporator.

The second heat exchanger is provided between the electrostatic precipitator and the flue-gas desulfurization device and recovers heat from an exhaust gas that moves from the electrostatic precipitator to the flue-gas desulfurization device. The second heat exchanger can recover heat until an exhaust gas at about 90° C. is lowered to about 60° C.

The second evaporator evaporates an organic solvent through use of heat recovered by the second heat exchanger to generate steam. As the organic solvent, a solvent having a low boiling point, which is to be evaporated with heat recovered from a low-temperature exhaust gas, is used. Examples of the organic solvent include ammonia, hydrochlorofluorocarbon, and hydrocarbon.

The second steam turbine is driven with steam generated by the second evaporator. The second steam turbine converts energy of the steam into a rotation movement via blades.

The second power generator generates power by the drive of the second steam turbine. The second power generator obtains electric energy from mechanical energy that is a rotation movement.

The second condenser condenses steam that has driven the second steam turbine to obtain an organic solvent.

The second medium pump is a pump that sends the condensed organic solvent from the second condenser to the second evaporator.

The above-mentioned power-generating device according to the present invention can include a cooling tower for circulating cooling water in the first condenser and/or the second condenser. Examples of the cooling tower include a cooling tower for circulating cooling water only in the first condenser, a cooling tower for circulating cooling water only in the second condenser, and a cooling tower for circulating cooling water in the first condenser and the second condenser.

As another embodiment mode different from the above-mentioned embodiment modes of the power-generating device of the present invention, the organic Rankine cycle system includes an exhaust gas treatment device, a first evaporator, a first steam turbine, a first power generator, a first condenser, a first medium pump, a second evaporator, a second steam turbine, a second power generator, a second condenser, and a second medium pump. The exhaust gas treatment device is as described above.

The exhaust gas treatment device, the first evaporator, the first steam turbine, the first power generator, the first condenser, the first medium pump constitute one organic Rankine cycle. Further, the exhaust gas treatment device, the second evaporator, the second steam turbine, the second power generator, the second condenser, and the second medium pump constitute another organic Rankine cycle.

The first evaporator is provided between the air preheater and the electrostatic precipitator, and evaporates an organic solvent through use of heat of an exhaust gas that moves from the air preheater to the electrostatic precipitator to generate steam. As the organic solvent, a solvent having a low boiling point, which is to be evaporated with heat recovered from a low-temperature exhaust gas, is used. Examples of the organic solvent include ammonia, hydrochlorofluorocarbon, and hydrocarbon.

The first steam turbine is driven with steam generated by the first evaporator. The first steam turbine converts energy of the steam into a rotation movement via blades.

The first power generator generates power by the drive of the first steam turbine. The first power generator obtains electric energy from mechanical energy that is a rotation movement.

The first condenser condenses steam that has driven the first steam turbine to obtain an organic solvent.

The first medium pump is a pump that sends the condensed organic solvent from the first condenser to the first evaporator.

The second evaporator is provided between the electrostatic precipitator and the flue-gas desulfurization device, and evaporates an organic solvent through use of heat of an exhaust gas that moves from the electrostatic precipitator to the flue-gas desulfurization device to generate steam. As the organic solvent, a solvent having a low boiling point, which is to be evaporated with heat recovered from a low-temperature exhaust gas, is used. Examples of the organic solvent include ammonia, hydrochlorofluorocarbon, and hydrocarbon.

The second steam turbine is driven with steam generated by the second evaporator. The second steam turbine converts energy of the steam into a rotation movement via blades.

The second power generator generates power by the drive of the second steam turbine. The second power generator obtains electric energy from mechanical energy that is a rotation movement.

The second condenser condenses steam that has driven the second steam turbine to obtain an organic solvent.

The second medium pump is a pump that sends the condensed organic solvent from the second condenser to the second evaporator.

The above-mentioned power-generating device according to the present invention can include a cooling tower for circulating cooling water in the first condenser and/or the second condenser. Examples of the cooling tower include a cooling tower for circulating cooling water only in the first condenser, a cooling tower for circulating cooling water only in the second condenser, and a cooling tower for circulating cooling water in the first condenser and the second condenser.

Next, a power-generating method of the present invention is described. The power-generating method of the present invention includes a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated in an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD).

As one embodiment mode of the power-generating method of the present invention, the step of executing an organic Rankine cycle includes a first heat recovery step, a second heat recovery step, a first steam generation step, a second steam generation step, a steam turbine drive step, a power generation step, a condensing step, and a transport step.

The first heat recovery step is a step of recovering heat from an exhaust gas that passes between the air preheater and the electrostatic precipitator. As an example, the first heat recovery step includes a step of setting a heat exchanger between the air preheater and the electrostatic precipitator to recover heat from an exhaust gas that moves from the air preheater to the electrostatic precipitator. During the first heat recovery step, heat can be recovered until an exhaust gas at about 150° C. is lowered to about 90° C.

The second heat recovery step is a step of recovering heat from an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device. As an example, the second heat recovery step includes a step of setting a heat exchanger between the electrostatic precipitator and the flue-gas desulfurization device to recover heat from an exhaust gas that moves from the electrostatic precipitator to the flue-gas desulfurization device. During the second heat recovery step, heat can be recovered until an exhaust gas at about 90° C. is lowered to about 60° C.

The first steam generation step is a step of evaporating an organic solvent through use of heat recovered in the first heat recovery step to generate steam. As an example, the first steam generation step includes a step of evaporating an organic solvent such as ammonia, hydrochlorofluorocarbon, and hydrocarbon with an evaporator through use of recovered heat to generate steam.

The second steam generation step is a step of evaporating an organic solvent through use of heat recovered in the second heat recovery step to generate steam. As an example, the second steam generation step includes a step of evaporating an organic solvent such as ammonia, hydrochlorofluorocarbon, and hydrocarbon with an evaporator through use of recovered heat to generate steam.

The steam turbine drive step is a step of driving a steam turbine with steam generated in the first steam generation step and the second steam generation step. During this step, energy of steam is converted into a rotation movement via blades.

The power generation step is a step of generating power in the steam turbine drive step. During this step, electric energy is obtained from mechanical energy that is a rotation movement.

The condensing step is a step of condensing steam that has driven the steam turbine to obtain an organic solvent. As an example, the condensing step includes a step of condensing steam with a condenser to obtain an organic solvent.

The transport step is a step of sending the organic solvent obtained by the condensation to the first steam generation step and the second steam generation step. As an example, the transport step includes a step of sending the organic solvent with a medium pump. The sent organic solvent is formed into steam in the first steam generation step and the second steam generation step to be used for generating power again.

As another embodiment mode different from the above-mentioned embodiment mode of the power-generating method of the present invention, the step of executing an organic Rankine cycle includes a first steam generation step, a second steam generation step, a steam turbine drive step, a power generation step, a condensing step, and a transport step.

The first steam generation step is a step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the air preheater and the electrostatic precipitator to generate steam. As an example, the first steam generation step includes a step of setting an evaporator between the air preheater and the electrostatic precipitator, to thereby evaporate an organic solvent such as ammonia, hydrochlorofluorocarbon, and hydrocarbon through use of heat of an exhaust gas that moves from the air preheater to the electrostatic precipitator to generate steam.

The second steam generation step is a step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device to generate steam. As an example, the second steam generation step includes a step of setting an evaporator between the electrostatic precipitator and the flue-gas desulfurization device, to thereby evaporate an organic solvent such as ammonia, hydrochlorofluorocarbon, and hydrocarbon through use of heat of an exhaust gas that moves from the air preheater to the electrostatic precipitator to generate steam.

The steam turbine drive step, the power generation step, the condensing step, and the transport step are as described above.

As still another embodiment mode different from the above-mentioned embodiment modes of the power-generating method of the present invention, the step of executing an organic Rankine cycle includes a first heat recovery step, a first steam generation step, a first steam turbine drive step, a first power generation step, a first condensing step, a first transport step, a second heat recovery step, a second steam generation step, a second steam turbine drive step, a second power generation step, a second condensing step, and a second transport step.

The first heat recovery step, the first steam generation step, the first steam turbine drive step, the first power generation step, the first condensing step, and the first transport step constitute one step of executing an organic Rankine cycle. Further, the second heat recovery step, the second steam generation step, the second steam turbine drive step, the second power generation step, the second condensing step, and the second transport step constitute another step of executing an organic Rankine cycle.

The first heat recovery step is a step of recovering heat from an exhaust gas that passes between the air preheater and the electrostatic precipitator. As an example, the first heat recovery step includes a step of setting a heat exchanger between the air preheater and the electrostatic precipitator to recover heat from an exhaust gas that moves from the air preheater to the electrostatic precipitator. During the first heat recovery step, heat can be recovered until an exhaust gas at about 150° C. is lowered to about 90° C.

The first steam generation step is a step of evaporating an organic solvent through use of heat recovered in the first heat recovery step to generate steam. As an example, the first steam generation step includes a step of evaporating an organic solvent such as ammonia, hydrochlorofluorocarbon, and hydrocarbon with an evaporator through use of recovered heat to generate steam.

The first steam turbine drive step is a step of driving a steam turbine with steam generated in the first steam generation step. During this step, energy of steam is converted into a rotation movement via blades.

The first power generation step is a step of generating power in the first steam turbine drive step. During this step, electric energy is obtained from mechanical energy that is a rotation movement.

The first condensing step is a step of condensing steam that has driven the first steam turbine to obtain an organic solvent. As an example, the first condensing step includes a step of condensing steam with a condenser to obtain an organic solvent.

The first transport step is a step of sending the organic solvent obtained by the condensation to the first steam generation step. As an example, the first transport step includes a step of sending the organic solvent with a medium pump. The sent organic solvent is formed into steam in the first steam generation step to be used for generating power again.

The second heat recovery step is a step of recovering heat from an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device. As an example, the second heat recovery step includes a step of setting a heat exchanger between the electrostatic precipitator and the flue-gas desulfurization device to recover heat from an exhaust gas that moves from the electrostatic precipitator to the flue-gas desulfurization device. During the second heat recovery step, heat can be recovered until an exhaust gas at about 90° C. is lowered to about 60° C.

The second steam generation step is a step of evaporating an organic solvent through use of heat recovered in the second heat recovery step to generate steam. As an example, the second steam generation step includes a step of evaporating an organic solvent with an evaporator to generate steam.

The second steam turbine drive step is a step of driving a steam turbine with steam generated in the second steam generation step. During this step, energy of steam is converted into a rotation movement via blades.

The second power generation step is a step of generating power in the second steam turbine drive step. During this step, electric energy is obtained from mechanical energy that is a rotation movement.

The second condensing step is a step of condensing steam that has driven the second steam turbine to obtain an organic solvent. As an example, the second condensing step includes a step of condensing steam with a condenser to obtain an organic solvent.

The second transport step is a step of sending the organic solvent obtained by the condensation to the second steam generation step. As an example, the second transport step includes a step of sending the organic solvent with a medium pump. The sent organic solvent is formed into steam in the second steam generation step to be used for generating power again.

As another embodiment mode different from the above-mentioned embodiment modes of the power-generating method of the present invention, the step of executing an organic Rankine cycle includes a first steam generation step, a first steam turbine drive step, a first power generation step, a first condensing step, a first transport step, a second steam generation step, a second steam turbine drive step, a second power generation step, a second condensing step, and a second transport step.

The first steam generation step, the first steam turbine drive step, the first power generation step, the first condensing step, and the first transport step constitute one step of executing an organic Rankine cycle. Further, the second steam generation step, the second steam turbine drive step, the second power generation step, the second condensing step, and the second transport step constitute another step of executing an organic Rankine cycle.

The first steam generation step is a step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the air preheater and the electrostatic precipitator to generate steam. As an example, the first steam generation step includes a step of setting an evaporator between the air preheater and the electrostatic precipitator, to thereby evaporate an organic solvent such as ammonia, hydrochlorofluorocarbon, and hydrocarbon through use of heat of an exhaust gas that moves from the air preheater to the electrostatic precipitator to generate steam.

The first steam turbine drive step is a step of driving a steam turbine with steam generated in the first steam generation step. During this step, energy of steam is converted into a rotation movement via blades.

The first power generation step is a step of generating power in the first steam turbine drive step. During this step, electric energy is obtained from mechanical energy that is a rotation movement.

The first condensing step is a step of condensing steam that has driven the first steam turbine to obtain an organic solvent. As an example, the first condensing step includes a step of condensing steam with a condenser to obtain an organic solvent.

The first transport step is a step of sending the organic solvent obtained by the condensation to the first steam generation step. As an example, the first transport step includes a step of sending the organic solvent with a medium pump. The sent organic solvent is formed into steam in the first steam generation step to be used for generating power again.

The second steam generation step is a step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device to generate steam. As an example, the second steam generation step includes a step of setting an evaporator between the electrostatic precipitator and the flue-gas desulfurization device, to thereby evaporate an organic solvent such as ammonia, hydrochlorofluorocarbon, and hydrocarbon through use of heat of an exhaust gas that moves from the air preheater to the electrostatic precipitator to generate steam.

The second steam turbine drive step is a step of driving a steam turbine with steam generated in the second steam generation step. During this step, energy of steam is converted into a rotation movement via blades.

The second power generation step is a step of generating power in the second steam turbine drive step. During this step, electric energy is obtained from mechanical energy that is a rotation movement.

The second condensing step is a step of condensing steam that has driven the second steam turbine to obtain an organic solvent. As an example, the second condensing step includes a step of condensing steam with a condenser to obtain an organic solvent.

The second transport step is a step of sending the organic solvent obtained by the condensation to the second steam generation step. As an example, the second transport step includes a step of sending the organic solvent with a medium pump. The sent organic solvent is formed into steam in the second steam generation step to be used for generating power again.

Hereinafter, embodiments of the present invention are described in detail with reference to the drawings. Note that, the present invention is not limited by the drawings.

FIG. 1 is a schematic diagram of a power-generating device according to an embodiment of the present invention. A power-generating device 1 uses, as a heat source, an exhaust gas treated by an exhaust gas treatment device 15 including an air preheater (APH) 10, an electrostatic precipitator (ESP) 20, and a flue-gas desulfurization device (FGD) 30. An exhaust gas sent from a boiler (not shown) is sent from A to B through the air preheater 10, the electrostatic precipitator 20, and the flue-gas desulfurization device 30 and discharged from a chimney pipe (not shown). Power generation is performed through use of heat recovered from the exhaust gas.

The power-generating device 1 includes, as a basic configuration, the exhaust gas treatment device 15, a first heat exchanger 40, a second heat exchanger 50, a first evaporator 60, a second evaporator 70, a steam turbine 80, a power generator 90, a condenser 100, and a medium pump 110. This basic configuration constitutes an organic Rankine cycle. Further, in order to condense steam in the condenser 100 efficiently, the power-generating device 1 includes a cooling tower 120 for circulating cooling water in the condenser 100.

Note that, a heat medium circulates between the first heat exchanger 40 and the first evaporator 60 and between the second heat exchanger 50 and the second evaporator 70.

The first heat exchanger 40 is provided between the air preheater 10 and the electrostatic precipitator 20 and recovers heat from an exhaust gas that moves from the air preheater 10 to the electrostatic precipitator 20. The first heat exchanger 40 recovers heat until an exhaust gas at about 150° C. is lowered to about 90° C. The second heat exchanger 50 is provided between the electrostatic precipitator 20 and the flue-gas desulfurization device 30 and recovers heat from an exhaust gas that moves from the electrostatic precipitator 20 to the flue-gas desulfurization device 30. The second heat exchanger 50 recovers heat until an exhaust gas at about 90° C. is lowered to about 60° C.

The first evaporator 60 evaporates an organic solvent through use of heat recovered in the first heat exchanger 40 to generate steam. The second evaporator 70 evaporates an organic solvent through use of heat recovered in the second heat exchanger 50 to generate steam.

The steam turbine 80 is driven with steam generated by the first evaporator 60 and the second evaporator 70. The power generator 90 generates power by the drive of the steam turbine 80. The condenser 100 condenses steam that has driven the steam turbine 80 to obtain an organic solvent. The medium pump 110 is a pump for sending the condensed organic solvent from the condenser 100 to the first evaporator 60 and the second evaporator 70.

FIG. 2 is a schematic diagram of a power-generating device according to another embodiment of the present invention in a form different from that of FIG. 1. A power-generating device 2 uses, as a heat source, an exhaust gas treated by an exhaust gas treatment device 15 including an air preheater 10, an electrostatic precipitator 20, and a flue-gas desulfurization device 30. Power generation is performed through use of heat recovered from the exhaust gas, that is, through use of an organic Rankine cycle.

The power-generating device 2 includes, as a basic configuration, the exhaust gas treatment device 15, a first evaporator 61, a second evaporator 71, a steam turbine 80, a power generator 90, a condenser 100, and a medium pump 110. This basic configuration constitutes the organic Rankine cycle. Further, the power-generating device 2 includes a cooling tower 120 for circulating cooling water in the condenser 100.

The first evaporator 61 is provided between the air preheater 10 and the electrostatic precipitator 20 and evaporates an organic solvent through use of heat of an exhaust gas that moves from the air preheater 10 to the electrostatic precipitator 20 to generate steam.

The second evaporator 71 is provided between the electrostatic precipitator 20 and the flue-gas desulfurization device 30 and evaporates an organic solvent through use of heat of an exhaust gas that moves from the electrostatic precipitator 20 to the flue-gas desulfurization device 30 to generate steam.

The steam turbine 80, the power generator 90, the condenser 100, and the medium pump 110 are similar to those of the power-generating device 1 of FIG. 1.

FIG. 3 is a schematic diagram of a power-generating device according to still another embodiment of the present invention in a form different from those of FIGS. 1 and 2. A power-generating device 3 uses, as a heat source, an exhaust gas treated by an exhaust gas treatment device 15 including an air preheater 10, an electrostatic precipitator 20, and a flue-gas desulfurization device 30.

The power-generating device 3 includes, as a basic configuration, the exhaust gas treatment device 15, a first heat exchanger 41, a first evaporator 62, a first steam turbine 81, a first power generator 91, a first condenser 101, a first medium pump 111, a second heat exchanger 51, a second evaporator 72, a second steam turbine 82, a second power generator 92, a second condenser 102, and a second medium pump 112. Further, the power-generating device 3 includes a cooling tower 121 and a cooling tower 122 for circulating cooling water in the condenser 101 and the condenser 102.

Note that, a heat medium circulates between the first heat exchanger 41 and the first evaporator 62 and between the second heat exchanger 51 and the second evaporator 72.

The exhaust gas treatment device 15, the first heat exchanger 41, the first evaporator 62, the first steam turbine 81, the first power generator 91, the first condenser 101, and the first medium pump 111 constitute one organic Rankine cycle. Further, the exhaust gas treatment device 15, the second heat exchanger 51, the second evaporator 72, the second steam turbine 82, the second power generator 92, the second condenser 102, and the second medium pump 112 constitute another organic Rankine cycle.

The first heat exchanger 41 is provided between the air preheater 10 and the electrostatic precipitator 20, and recovers heat from an exhaust gas that moves from the air preheater 10 to the electrostatic precipitator 20. The first heat exchanger 41 recovers heat until an exhaust gas at about 150° C. is lowered to about 90° C. The first evaporator 62 evaporates an organic solvent through use of heat recovered by the first heat exchanger 41 to generate steam. The first steam turbine 81 is driven with steam generated by the first evaporator 62. The first power generator 91 generates power by the drive of the first steam turbine 81. The first condenser 101 condenses steam that has driven the first steam turbine 81 to obtain an organic solvent. The first medium pump 111 is a pump for sending the condensed organic solvent from the first condenser 101 to the first evaporator 62.

The second heat exchanger 51 is provided between the electrostatic precipitator 20 and the flue-gas desulfurization device 30, and recovers heat from an exhaust gas that moves from the electrostatic precipitator 20 to the flue-gas desulfurization device 30. The second heat exchanger 51 recovers heat until an exhaust gas at about 90° C. is lowered to about 60° C. The second evaporator 72 evaporates an organic solvent through use of heat recovered by the second heat exchanger 51 to generate steam. The second steam turbine 82 is driven with steam generated by the second evaporator 72. The second power generator 92 generates power by the drive of the second steam turbine 82. The second condenser 102 condenses steam that has driven the second steam turbine 82 to obtain an organic solvent. The second medium pump 112 is a pump for sending the condensed organic solvent from the second condenser 102 to the second evaporator 72.

FIG. 4 is a schematic diagram of a power-generating device according to another embodiment of the present invention in a form different from those of FIGS. 1, 2, and 3. A power-generating device 4 uses, as a heat source, an exhaust gas treated by an exhaust gas treatment device 15 including an air preheater 10, an electrostatic precipitator 20, and a flue-gas desulfurization device 30.

The power-generating device 4 includes, as a basic configuration, the exhaust gas treatment device 15, a first evaporator 63, a first steam turbine 81, a first power generator 91, a first condenser 101, and a first medium pump 111, a second evaporator 73, a second steam turbine 82, a second power generator 92, a second condenser 102, and a second medium pump 112. Further, the power-generating device 4 includes a cooling tower 121 and a cooling tower 122 for circulating cooling water in the condenser 101 and the condenser 102.

The exhaust gas treatment device 15, the first evaporator 63, the first steam turbine 81, the first power generator 91, the first condenser 101, and the first medium pump 111 constitute one organic Rankine cycle. Further, the exhaust gas treatment device 15, the second evaporator 73, the second steam turbine 82, the second power generator 92, the second condenser 102, and the second medium pump 112 constitute another organic Rankine cycle.

The first evaporator 63 is provided between the air preheater 10 and the electrostatic precipitator 20 and evaporates an organic solvent through use of heat of an exhaust gas that moves from the air preheater 10 to the electrostatic precipitator 20 to generate steam.

The second evaporator 73 is provided between the electrostatic precipitator 20 and the flue-gas desulfurization device 30 and evaporates an organic solvent through use of heat of an exhaust gas that moves from the electrostatic precipitator 20 to the flue-gas desulfurization device 30 to generate steam.

The first steam turbine 81, the first power generator 91, the first condenser 101, the first medium pump 111, the second steam turbine 82, the second power generator 92, the second condenser 102, and the second medium pump 112 are similar to those of the power-generating device 3 of FIG. 3.

While there have been described what are at present considered to be certain embodiments of the invention, the present invention is not limited to the embodiments described above, and various modifications and changes can be made thereto based on the technical idea of the present invention. 

What is claimed is:
 1. A power-generating device, comprising an organic Rankine cycle system using heat recovered from an exhaust gas, wherein the organic Rankine cycle system comprises: an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD); a first heat exchanger provided between the air preheater and the electrostatic precipitator; a second heat exchanger provided between the electrostatic precipitator and the flue-gas desulfurization device, a first evaporator for evaporating an organic solvent through use of heat recovered by the first heat exchanger to generate steam; a second evaporator for evaporating an organic solvent through use of heat recovered by the second heat exchanger to generate steam; a steam turbine to be driven with steam generated by the first evaporator and the second evaporator; a power generator for generating power by a drive of the steam turbine; a condenser for condensing steam that has driven the steam turbine to obtain an organic solvent; and a medium pump for sending the condensed organic solvent from the condenser to the first evaporator and the second evaporator.
 2. A power-generating device according to claim 1, further comprising a cooling tower for circulating cooling water in the condenser.
 3. A power-generating device, comprising an organic Rankine cycle system using heat recovered from an exhaust gas, wherein the organic Rankine cycle system comprises: an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD); a first evaporator provided between the air preheater and the electrostatic precipitator, for evaporating an organic solvent to generate steam; a second evaporator provided between the electrostatic precipitator and the flue-gas desulfurization equipment, for evaporating an organic solvent to generate steam; a steam turbine to be driven with steam generated by the first evaporator and the second evaporator; a power generator for generating power by a drive of the steam turbine; a condenser for condensing steam that has driven the steam turbine to obtain an organic solvent; and a medium pump for sending the condensed organic solvent from the condenser to the first evaporator and the second evaporator.
 4. A power-generating device according to claim 3, further comprising a cooling tower for circulating cooling water in the condenser.
 5. A power-generating device, comprising an organic Rankine cycle system using heat recovered from an exhaust gas, wherein the organic Rankine cycle system comprises: an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD); a first heat exchanger provided between the air preheater and the electrostatic precipitator; a first evaporator for evaporating an organic solvent through use of heat recovered by the first heat exchanger to generate steam; a first steam turbine to be driven with steam generated by the first evaporator; a first power generator for generating power by a drive of the first steam turbine; a first condenser for condensing steam that has driven the first steam turbine to obtain an organic solvent; a first medium pump for sending the condensed organic solvent from the first condenser to the first evaporator; a second heat exchanger provided between the electrostatic precipitator and the flue-gas desulfurization device; a second evaporator for evaporating an organic solvent through use of heat recovered by the second heat exchanger to generate steam; a second steam turbine to be driven with steam generated by the second evaporator; a second power generator for generating power by a drive of the second steam turbine; a second condenser for condensing steam that has driven the second steam turbine to obtain an organic solvent; and a second medium pump for sending the condensed organic solvent from the second condenser to the second evaporator.
 6. A power-generating device according to claim 5, further comprising a cooling tower for circulating cooling water in at least one of the first condenser and the second condenser.
 7. A power-generating device, comprising an organic Rankine cycle system using heat recovered from an exhaust gas, wherein the organic Rankine cycle system comprises: an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD); a first evaporator provided between the air preheater and the electrostatic precipitator, for evaporating an organic solvent to generate steam; a first steam turbine to be driven with steam generated by the first evaporator; a first power generator for generating power by a drive of the first steam turbine; a first condenser for condensing steam that has driven the first steam turbine to obtain an organic solvent; a first medium pump for sending the condensed organic solvent from the first condenser to the first evaporator; a second evaporator provided between the electrostatic precipitator and the flue-gas desulfurization device, for evaporating an organic solvent to generate steam; a second steam turbine to be driven with steam generated by the second evaporator; a second power generator for generating power by a drive of the second steam turbine; a second condenser for condensing steam that has driven the second steam turbine to obtain an organic solvent; and a second medium pump for sending the condensed organic solvent from the second condenser to the second evaporator.
 8. A power-generating device according to claim 7, further comprising a cooling tower for circulating cooling water in at least one of the first condenser and the second condenser.
 9. A power-generating method, comprising a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated by an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD), wherein the step of executing an organic Rankine cycle comprises: a first heat recovery step of recovering heat from an exhaust gas that passes between the air preheater and the electrostatic precipitator; a second heat recovery step of recovering heat from an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device; a first steam generation step of evaporating an organic solvent through use of heat recovered in the first heat recovery step to generate steam; a second steam generation step of evaporating an organic solvent through use of heat recovered in the second heat recovery step to generate steam; a steam turbine drive step of driving a steam turbine with steam generated in the first steam generation step and the second steam generation step; a power generation step of generating power in the steam turbine drive step; a condensing step of condensing steam that has driven the steam turbine to obtain an organic solvent; and a transport step of sending the organic solvent obtained by the condensation to the first steam generation step and the second steam generation step.
 10. A power-generating method, comprising a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated by an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD), wherein the step of executing an organic Rankine cycle comprises: a first steam generation step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the air preheater and the electrostatic precipitator to generate steam; a second steam generation step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device to generate steam; a steam turbine drive step of driving a steam turbine with steam generated in the first steam generation step and the second steam generation step; a power generation step of generating power in the steam turbine drive step; a condensing step of condensing steam that has driven the steam turbine to obtain an organic solvent; and a transport step of sending the organic solvent obtained by the condensation to the first steam generation step and the second steam generation step.
 11. A power-generating method, comprising a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated by an exhaust gas treatment device comprising an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD), wherein the step of executing an organic Rankine cycle comprises: a first heat recovery step of recovering heat from an exhaust gas that passes between the air preheater and the electrostatic precipitator; a first steam generation step of evaporating an organic solvent through use of heat recovered in the first heat recovery step to generate steam; a first steam turbine drive step of driving a first steam turbine with steam generated in the first steam generation step; a first power generation step of generating power in the first steam turbine drive step; a first condensing step of condensing steam that has driven the first steam turbine to obtain an organic solvent; a first transport step of sending the organic solvent obtained by the condensation to the first steam generation step; a second heat recovery step of recovering heat from an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device; a second steam generation step of evaporating an organic solvent through use of heat recovered in the second heat recovery step to generate steam; a second steam turbine drive step of driving a second steam turbine with steam generated in the second steam generation step; a second power generation step of generating power in the second steam turbine drive step; a second condensing step of condensing steam that has driven the second steam turbine to obtain an organic solvent; and a second transport step of sending the organic solvent obtained by the condensation to the second steam generation step.
 12. A power-generating method, comprising a step of executing an organic Rankine cycle using heat recovered from an exhaust gas treated by an exhaust gas treatment device including an air preheater (APH), an electrostatic precipitator (ESP), and a flue-gas desulfurization device (FGD), wherein the step of executing an organic Rankine cycle comprises: a first steam generation step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the air preheater and the electrostatic precipitator to generate steam; a first steam turbine drive step of driving a first steam turbine with steam generated in the first steam generation step; a first power generation step of generating power in the first steam turbine drive step; a first condensing step of condensing steam that has driven the first steam turbine to obtain an organic solvent; a first transport step of sending the organic solvent obtained by the condensation to the first steam generation step; a second steam generation step of evaporating an organic solvent through use of heat of an exhaust gas that passes between the electrostatic precipitator and the flue-gas desulfurization device to generate steam; a second steam turbine drive step of driving a second steam turbine with steam generated in the second steam generation step; a second power generation step of generating power in the second steam turbine drive step; a second condensing step of condensing steam that has driven the second steam turbine to obtain an organic solvent; and a second transport step of sending the organic solvent obtained by the condensation to the second steam generation step. 